Device for controlling the quantity of air admitted to a supercharged internal combustion engine and method using such a device dispositif

ABSTRACT

The present invention is a device for controlling a quantity of air introduced into an inlet of a boosted internal combustion engine with the engine having exhaust gas outlets each connected to an exhaust manifold of at least one cylinder. The device includes a boosting device comprising a turbocharger having a turbine with intakes connected to the exhaust gas outlets, an external-air compressor and a duct for partially transferring the compressed air from the compressor to the intakes. The partial transfer duct has branches connected to the turbine intakes which each have valve regulation for controlling circulation of compressed air in the branches.

CROSS-REFERENCE TO RELATED APPLICATIONS

Reference is made to International Application No. PCT/EP2015/064282filed Jun. 24, 2015 and French Application No. 14/57,141 filed Jul. 24,2014, which are hereby incorporated herein by reference in theirentirety.

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to a device for controlling the quantity of airintroduced into the inlet of a boosted internal combustion engine,particularly a stationary engine or one for a motor vehicle orcommercial vehicle and a method of controlling the quantity of air forsuch an engine.

Description of the Prior Art

As is widely known, the power delivered by an internal combustion engineis dependent on the quantity of air introduced into the engine'scombustion chamber which is proportional to the density of this air.

Therefore, it is customary to increase this quantity of air bycompressing external air before it is let into this combustion chamber.This operation, which is called boosting, can be carried out by anymeans, such as a turbocharger or a mechanically driven compressor, whichmay be centrifugal or of the positive-displacement type.

In the case of boosting by a turbocharger, the latter comprises a singleflow or double flow rotary turbine, connected by a shaft to a rotarycompressor. The exhaust gases coming from the engine pass through theturbine which is then rotatingly driven. This rotation is thentransmitted to the compressor which, by its very rotation, compressesthe external air before it is introduced into the combustion chamber.

As is better described in French patent application 2 478 736, in orderto significantly increase this quantity of compressed air in the enginecombustion chamber, it is intended to increase the compression ofexternal air by the compressor further still.

This is effected more particularly by increasing the speed of rotationof the turbine and therefore of the compressor.

For this, a portion of the compressed air coming out of the compressoris diverted to be let directly into the turbine intake to mix with theexhaust gases. This turbine is then crossed by a greater quantity offluid (a mixture of compressed air and exhaust gas), whereby the speedof rotation of the turbine and consequently of the compressor can beincreased. Therefore, with this compressor speed increase, it ispossible to increase the pressure of the external air which will becompressed in this compressor and then introduced into the enginecombustion chamber.

Due to this, the compressed air is of a higher density whereby thequantity of air contained by the combustion chamber can be increased.

This type of boosted engine, although satisfactory, nevertheless hassome significant drawbacks.

In fact, if the flow rate of the compressed air which is let into theturbine intake is not correctly controlled, this may lead to an enginemalfunction.

Therefore, by way of example, in the event of too great a quantity ofcompressed air being diverted to the turbine intake, the exhaust gasesentering the turbine are cooled too much by this air and bring about areduction in the overall performance of the boosting.

SUMMARY OF THE INVENTION

The present invention rectifies the aforementioned drawbacks by means ofa device for controlling the quantity of air introduced into the intakeof a boosted internal combustion engine with which it is possible torespond to all the engine's power requirements.

With the invention it is also possible to carry out a transfer ofcompressed air from the inlet to the exhaust even when the mean pressureof the compressed air in the inlet is lower than that of the gases inthe exhaust. It is simply sufficient that there are phases during theengine operation cycle where the pressure in the inlet is higher thanthat in the exhaust.

To this end, the present invention is to a device for controlling thequantity of air introduced into the inlet of a boosted internalcombustion engine. The engine comprises two exhaust gas outlets withoutlet being each connected to an exhaust manifold of at least onecylinder. The invention comprises a boosting device with a turbochargercomprising a double intake turbine connected to the exhaust gas outletsas well as an external-air compressor and a duct for partial transfer ofthe compressed air from the compressor to the turbine intakes whereinthe partial transfer duct comprises two branches connected to theturbine intakes which each carry a valve regulator controlling thecirculation of the compressed air in these branches.

Advantageously, the branches can each also carry a non-return valve.

One of the branches can be connected to the other branch with aconnecting line.

The connecting line can carry valve regulation.

The valve regulation can comprise proportional valves.

The transfer duct can carry heating for the compressed air circulatingtherein.

The heating can comprise a heat exchanger.

The heat exchanger can comprise an intake for exhaust gas coming fromthe turbocharger turbine and an exhaust gas outlet to the exhaust line.

The invention also relates to a method of controlling the quantity ofcompressed air in the inlet of a boosted internal combustion engine. Theengine comprises two exhaust gas outlets with each outlet beingconnected to an exhaust manifold of a at least one cylinder. Theinvention comprises a boosting device with a turbocharger with a doubleintake turbine connected to the exhaust gas outlets as well as anexternal-air compressor and a duct for partial transfer of thecompressed air from the compressor to the turbine intakes, wherein aportion of the compressed air is introduced from the compressor into theturbine's exhaust gas intake sections.

The method can divide the transfer duct into two branches and cancontrolling the circulation of the compressed air in each of thebranches with valve regulation means.

The method can connecting one of the branches to the other branch with aconnecting line.

The method can consist of heating the compressed air circulating in thetransfer duct before intake into the turbine.

BRIEF DESCRIPTION OF THE DRAWINGS

The other features and benefits of the invention will appear fromreading the description which is to follow, given for solelyillustrative purposes and on a non-limiting basis and to which thefollowing are attached:

FIG. 1 illustrates an internal combustion engine with a boosting deviceaccording to the invention;

FIG. 2 shows a variant of the internal combustion engine with itsboosting device and

FIG. 3 illustrates a variant of the internal combustion engine with itsboosting device according to FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, the internal combustion engine 10 comprises at least twocylinders, which here are four cylinders referenced 12 ₁ to 12 ₄ fromthe left of the figure.

Preferably, this engine is a direct injection internal combustionengine, particularly of the Diesel type but this in no way excludes anyother type of internal combustion engine.

Each cylinder comprises an inlet means 14 or inlet with at least oneinlet valve 16. Here two inlet valves each controlling an induction pipe18. The induction pipes 18 end at an inlet manifold 20 supplied by asupply duct 22 with inlet air, such as compressed air.

This cylinder also comprises burned gas exhaust means 24 or exhaust withat least one exhaust valve 26. Here two valves, control an exhaust tubeor lines 28.

In the example illustrated, the engine is prepared for operating with afiring order of 1-3-4-2. In view of this firing order, the exhaust tubesor lines of the first cylinder 12 ₁ and second cylinder 12 ₄, which forma first unit of at least one cylinder, are connected to a first exhaustmanifold 30 with a first exhaust gas outlet 32. The exhaust tubes orlines of the third and fourth cylinders 12 ₂ and 12 ₃, which form asecond unit of at least one cylinder, are connected to a second exhaustmanifold 34 which comprises a second exhaust gas outlet 36.

The two exhaust gas outlets lead to a turbocharger 38 for compressingair and more particularly to the expansion turbine 40 of thisturbocharger.

As illustrated in FIG. 1, the turbocharger is a double intaketurbocharger, better known by the term “Twin Scroll” turbocharger.

This type of turbocharger comprises the expansion turbine 40 which isswept by the exhaust gases and rotatingly connected, by a shaft 42, to acompressor 44.

At the turbine, the exhaust gas intake is divided into two sections. Afirst intake section 46 is connected to the first exhaust gas outlet 32of the first manifold 30 and a second intake section 48 is connected tothe second exhaust gas outlet 36 of the second exhaust manifold 34.

The gas discharge 50 of the turbine 40 is conventionally connected tothe engine's exhaust line 52.

The compressor 44 of the turbocharger 38 comprises an external-air inlet54 supplied by a supply duct 56. This compressor's compressed air outlet58 is connected to the supply duct 22 of the inlet manifold 20 by a duct60.

Advantageously, it can be arranged to place a compressed air cooler 62on the duct 60, between the compressor and the duct 22.

As can be seen better in FIG. 1, with a transfer duct 64, a portion ofthe compressed air coming out of the compressor 44 can be made tocirculate to the turbine intakes 46 and 48.

More precisely, this partial transfer duct starts in the duct 60, at anintersection point 66 between the compressor and the cooler 62 and isthen divided, from a bifurcation point 68, into two branches 70 and 72.The branch 70 leads to the turbine intake 46 via its connection to thefirst exhaust gas outlet 32 and the branch 72 leads to this turbine'sother intake 48 via its connection to the exhaust gas outlet 36.

Each branch carries valve regulation means of regulation 74 and 76, suchas a proportional valve, controlled by a control means 78, which can becommon to the two valve regulation means. Therefore, with this valve,the circulation of the compressed air in the branch can be controlled.

Advantageously, each branch also comprises a non-return valve 80 and 82which prevents the circulation of the compressed air from the branch tothe compressor, while preventing the two branches from coming intocommunication.

Therefore, with this configuration, it is possible during operation ofthe engine to take advantage of the zones of low exhaust pressureprevailing intermittently in the exhaust manifolds to introducecompressed air into the turbine and thus to increase the flow rate ofthis turbine and consequently of the compressor. With this, it is alsopossible to have more efficient boosting for low engine speeds.

During operation, in case of a requirement for air in a large quantityin the cylinders, the valves 74 and 76 are made to open to introducecompressed air from the compressor 44 into the turbine 40.

The compressed air coming from the compressor 44 circulates in the duct64 and then in the branches 70 and 72 to reach the exhaust gas intakes46 and 48 of the turbine 40, delivering surplus fluid to this turbine.

Therefore, the turbine is swept not only by the exhaust gases from theoutlets 32 and 36 but also by compressed air which is added to thesegases. Because of this, turbine rotation is increased, which causes anincrease in compressor rotation and consequently an increase in thepressure of the compressed air which comes from this compressor.

Of course, the valves 74 and 76 are controlled by the control means orcontrol 78 so as to let into the turbine the quantity of compressed airwhich meets the engine's boosting requirements.

The variant in FIG. 2 can be distinguished from FIG. 1 due to theplacing of a connecting duct 84 between the two branches 70 and 72. Thisduct is provided with a regulation valve means or regulation 86, such asa proportional valve which, here, is also controlled by the controlmeans or control 78.

One of the ends of this duct is connected to the branch 70 at a pointsituated between the valve 74 and the exhaust gas outlet 32 and theother end is connected at a point situated between the valve 76 and theexhaust gas outlet 36.

With this duct, it is possible to control the communication of fluidbetween the two branches reaching the turbine.

More precisely, with this connecting duct, it is possible to divert aportion of the compressed air circulating in one of the branches tointroduce it into the other branch, mixing with the exhaust gases at theintakes of the turbine 40.

Furthermore, with the connecting duct, it is possible to restore in onebranch of the turbine the pressure differential of the exhaust gases (orpulsating exhaust) of the other branch which is angularly offset in theengine combustion cycle.

In FIG. 3, which essentially comprises the same elements as those inFIG. 1, the compressed air leaving the compressor 44 and circulating inthe transfer duct 64 is heated before being introduced into the turbine40.

For this purpose, the transfer duct 64 carries a means of heater 88 forheating the compressed air, which here is a heat exchanger in the formof a heat radiator, placed between the intersection point 66 and thebifurcation point 68 of the duct. This radiator is crossed by thecompressed air which circulates in this duct while being swept by theengine exhaust gases. These exhaust gases come from the turbinedischarge 50 and are conveyed by a duct 90 to the radiator intake 92.The exhaust gases sweep this radiator, transferring the heat theycontain to the compressed air, subsequently to leave this radiator againthrough the outlet 94, to be directed to the engine exhaust line.

Therefore, a portion of the exhaust gas energy is recovered by thecompressed air which is introduced into the turbine through one or otherof the intakes 46 and 48.

Therefore, with this heated compressed air, it is possible to supplyextra energy to the turbine which, as a result, will rotate at a higherspeed. This high speed of rotation is then transmitted to thecompressor, which will carry out higher compression of external air.

1-12. (canceled)
 13. A device for controlling a quantity of airintroduced into an inlet of a boosted internal combustion engine withthe engine including exhaust gas outlets, connected to an exhaustmanifold of at least one cylinder comprising: a boosting devicecomprising a turbocharger including a turbine having intakes connectedto the exhaust gas outlets, an external-air compressor and a duct forpartial transfer of the compressed air from the compressor to theintakes; and wherein the partial transfer duct comprises branchesconnected to the intakes with each branch including valve regulationwhich controls circulation of compressed air in the branches of thepartial transfer duct.
 14. A device according to claim 13, wherein thebranches each also include a non-return valve which prevents circulationof compressed air back to the compressor.
 15. A device according toclaim 13, wherein one of the branches is connected to the other branchwith a connecting line.
 16. A device according to claim 14, wherein oneof the branches is connected to the other branch with a connecting line.17. A device according to claim 15, wherein the connecting line includesvalve regulation.
 18. A device according to claim 16, wherein theconnecting line includes valve regulation.
 19. A device according toclaim 17, wherein the valve regulation comprises proportional valves.20. A device according to claim 18, wherein the valve regulationcomprises proportional valves.
 21. A device according to claim 13,wherein the duct for partial transfer includes a heater for heatingcompressed air circulating therein.
 22. A device according to claim 21,wherein in that the heater comprises a heat exchanger.
 23. A deviceaccording to claim 22, wherein the heater comprises an intake forexhaust gas coming from the turbine and an exhaust gas outlet to anexhaust line.
 24. A method for controlling a quantity of compressed airinto an inlet of a boosted internal combustion engine with the engineincluding exhaust gas outlets connected to an exhaust manifold of atleast one cylinder, a device comprising a boosting device including aturbocharger having a turbine with intakes connected to the exhaust gasoutlets, an external-air compressor and a duct for partial transfer ofthe compressed air from the compressor to the intakes, comprising thesteps of compressing external-air and introducing a portion of thecompressed air coming from the compressor into exhaust gas intakesections of the turbine.
 25. A method according to claim 24, comprisingdividing the duct for partial transfer into two branches and controllingcirculation of the compressed air in each of the branches withregulation valves.
 26. A method according to claim 24, comprisingconnecting one of the branches to the other branch with a connectingline.
 27. A method according to claim 24, comprising heating thecompressed air circulating in the transfer duct before flowing into theturbine.